Influence of the particle size of encapsulated chia oil on the oil release and bioaccessibility during in vitro gastrointestinal digestion.

Among vegetable oils, chia oil has been gaining interest in recent years due to its high linolenic acid content (ALA, 18:3 ω3). The aim of this work was to study the influence of the particle size of encapsulated purified chia oil (PCO) on the encapsulation efficiency and PCO release during in vitro digestion. PCO micro- and nano-sized particles with sodium alginate (SA) as an encapsulating agent (ME-PCO-SA and NE-PCO-SA) were designed by micro and nano spray-drying, respectively, applying a central composite plus star point experimental design. NE-PCO-SA showed a smaller particle size and higher encapsulation efficiency of PCO than ME-PCO-SA (0.16 µm vs. 3.5 µm; 98.1% vs. 92.0%). Emulsions (NE-PCO and ME-PCO) and particles (NE-PCO-SA and ME-PCO-SA) were subjected to in vitro static gastrointestinal digestion. ME-PCO and NE-PCO showed sustained oil release throughout the three phases of digestion (oral, gastric and intestinal phases), whereas the PCO release from ME-PCO-SA and NE-PCO-SA occurred mainly in the intestinal phase, showing the suitability of sodium alginate as an intestine-site release polymer. Nano-sized particles showed a significantly higher PCO release after in vitro digestion (NE-PCO-SA, 78.4%) than micro-sized particles (ME-PCO-SA, 69.8%), and also higher bioaccessibility of individual free fatty acids, such as C18:3 ω-3 (NE-PCO-SA, 23.6%; ME-PCO-SA, 7.9%), due to their greater surface area. However, when ME-PCO-SA and NE-PCO-SA were incorporated into yogurt, the PCO release from both particle systems after the digestion of the matrix was similar (NE-PCO-SA, 58.8%; ME-PCO-SA-Y, 61.8%), possibly because the calcium ions contained in the yogurt induced partial ionic gelation of SA, impairing the PCO release. Sodium alginate spray-dried micro and nanoparticles showed great potential for vehiculation of omega-3 rich oils in the design of functional foods.

Evaluation of Polyphenol Content and Antioxidant Capacity of Fruits and Vegetables Using a Modified Enzymatic Extraction.

Fruits and vegetables are considered a good source of polyphenols and antioxidant capacities which are beneficial in protecting the human body against damage induced by reactive species. The objective of this work is to conduct an assessment of the polyphenol content and antioxidant activities of different fruit (kiwi, pear, green apple, raspberry, blackberry, strawberry and blueberry) and vegetable (pumpkin, green and red pepper) extracts using both chemical extraction and a modified in vitro digestive enzymatic extraction in order to compare results. Polyphenol content and antioxidant capacity of different fruits, vegetables and fruit juices were determined by Folin-Ciocalteu and FRAP methods, respectively. It was observed that polyphenol content expressed as gallic acid equivalents of extracts obtained with the two extraction methods was significantly (p<0.05) different (on average 310.3 and 231.8 mg per 100 g of fresh sample in enzymatic and methanolic extracts, respectively). Antioxidant capacity was also significantly (p<0.05) different in the extracts obtained by the two methods, with higher values in enzymatic extracts (1.91 mmol of Fe2+ per 100 g of fresh sample). Analyses of apple samples with and without skin also revealed important differences related to methodology and composition. Additionally, the original enzymatic extraction method was improved to avoid interferences caused by the presence of protein residues in the extract.